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有源电力滤波器(active power filter,APF)电流环控制要求补偿电流无误差地跟踪给定信号,传统的dq坐标系下P I控制很难消除稳态误差。采用并联的比例谐振(proportional resonant,PR)控制器,对不同频率的正弦分量进行跟踪控制,实现零稳态误差跟踪。针对电网频率波动和三相不平衡问题,在坐标系下采用改进PR控制器实现电流跟踪控制。在详细分析PR控制器各参数对性能指标影响的基础上,总结参数的调试方法,并给出控制器离散化方法。通过仿真与实验对所提控制策略进行验证,APF投入后,电网电流畸变率下降,中线电流有效值减小,负载和频率波动时仍有较好的补偿效果。该结果表明,所提的改进PR控制策略可以有效地抑制谐波,较好地解决三相不平衡问题,对负载突变和频率波动均有良好的适应性。
The current loop control of active power filter (APF) requires that the compensation current should track a given signal without error. It is difficult to eliminate the steady-state error in the conventional PID control of dq coordinate system. The parallel resonant proportional (PR) controller is used to track and control sinusoidal components with different frequencies to achieve zero-steady-state error tracking. Aiming at the problem of grid frequency fluctuation and three-phase unbalance, the improved PR controller is used to realize the current tracking control under the coordinate system. Based on the detailed analysis of the influence of each parameter of PR controller on the performance index, the debugging method of parameters is summarized and the controller discretization method is given. After simulation and experiment, the proposed control strategy is verified. After the APF is put into operation, the current distortion rate of the power grid decreases and the RMS value of the neutral current decreases. When the load and frequency fluctuate, there is still a good compensation effect. The results show that the proposed improved PR control strategy can effectively suppress harmonics, solve the problem of three-phase unbalance problem well, and have good adaptability to load mutation and frequency fluctuation.